I have an employer issued Windows laptop. I have it connected to a charger on my desk almost all day. It is very often the case, that I close the lid and after some time it gets hot and the fan gets very loud. I always wonder: "what the fuck is this stupid machine doing?", it can't be an update, because Windows is incapable of doing unattended updates without a restart. After I open the lid the next day nothing seems to have happened. Same with my wife's work laptop. Her laptop is even worse, because sometimes it will play the sound of an incoming e-mail in the middle of the night.
It is entirely bizarre.